The background of the invention will be discussed in two parts:
1. Field of the Invention
This invention relates to bicycle brake shoe assemblies, and more particularly to adjustable bicycle brake assemblies having a circular finned heat sink and removable, replaceable brake shoes.
2. Description of the Prior Art
In present day bicycle designs, and particularly bicycles of the lightweight type, the rims are narrow and braking is effected by brake assemblies having brake shoes of friction material configured for urging against the sides of the rims. In most popular bicycles of this type, caliper brake assemblies are ordinarily used. Such caliper brake assemblies have manually actuated brake arms pivotally secured to the frame, with the arms configured for depending down around the tire with the ends of the arms in proximate relation to the opposing sides of the rims. The lower ends of the arms are slotted for receiving brake shoes which have studs for extending through the slots for adjusting the position of the brake pad relative to the rim surface.
In conventional brake shoes of this type, the shoe includes a pad of friction material in generally rectangular configuration bonded to, or molded about a fastener having a rectangular head, the stud of the fastener being passed through the slotted brake arm ends. Other known brake shoes have a metal housing into which is pushed or inserted a block of friction material. With such prior art brake shoes, the transfer of heat generated by the braking action is poor.
An attempt has been made to rectify the poor heat transfer, this attempt being exemplified by the device shown and described in U.S. Pat. No. 4,036,333 for "Bicycle Brake Shoe with Heat Dissipating Means", issued July 19, 1977 to William R. Mathauser. The device of this patent is a finned brake shoe with a pad of friction material thermally bonded thereto. The fins of the brake shoe extend the length of the brake shoe which is generally rectangular in configuration. The patent discloses an alternative embodiment of brake shoe in which a housing having a slotted opening received therein a generally parallelepiped shaped pad of friction material with an intervening strip of metal.
With the first brake shoe of the Mathauser Patent, upon wear of the friction pad, the entire shoe, including the finned heat sink, is discarded and replaced as a unit, thus being relatively uneconomical. In the second embodiment, the inserted pad with the metal strip would appear to be technically inferior due to the possibility of sliding of the pad relative to the housing during braking, unless the pad is suitably bonded to the housing.
It is an object of the present invention to provide a new and improved adjustable bicycle brake assembly.
It is another object of the present invention to provide a new and improved brake assembly having a finned heat sink separable from a brake shoe which may be discarded upon wear of the pad.
It is a further object of the present invention to provide a new and improved brake assembly having a heat sink member with generally disk-shaped fins and a peripheral lip forming a recess for receiving a separable brake shoe device.
It is still another object of the present invention to provide a new and improved brake assembly having improved heat transfer characteristics in an economical configuration.
It is a still further object of the present invention to provide a new and improved fastener for enabling adjustment of the position of the brake shoe relative to the rim.